Safety stop for drum travel



D. M L. DUNCAN SAFETY STOP FOR DRUM TRAVEL April 4, 1950 Filed April 2, 1946 Y INVENTOR. DAN/EL MLEAN DUNCAN A 7' TORNEV Patented Apr. 4, 1950 SAFETY STOP FOR DRUM TRAVEL Daniel McLean Duncan, Los Angeles, Calif., assignor to Emsco Derrick & Equipment Company, Los Angeles, Calif., a corporation of California Application April 2, 1946, Serial No. 659,064

3 Claims. 1

My invention relates to hoisting equipment such as employed in oil well derricks, and relates in particular to hoisting equipment of this character having an emergency safety stop mechanism for preventing accidents resulting from over-travel of parts of the hoisting equipment.

The hoisting equipment ordinarily employed in oil well derricks includes a block and tackle, the cable of which block and tackle is spooled on the drum of the rotary drawworks. The drum is rotated by power received through a clutch and brakes are provided therefor to control rotation of the drum when power is not applied. Very serious accidents may be caused by breakage of cable, crown block, sheaves and traveling block parts occurring when the traveling block of the hoisting equipment is pulled up against the top structure or crown block of the derrick as the result of failure of the operator to release the clutch when the traveling block has been pulled up to the safe limit of its upward travel. The lives of many persons working in derricks are in the keeping of the driller who operates the drawworks. If he does not exercise constant vigilance, serious accidents may result. Night conditions of operation, direct suns rays and distractions make such vigilance difficult.

It is an object of the invention to provide hoisting equipment of this character having means which will automatically stop the drum of the drawworks and apply the brakes thereof when the traveling block has reached the safe limit of its upward travel.

It is an object of the invention to provide in hoisting equipment a control member arranged so that it will be engaged by a moving part of the hoisting equipment when all of the parts of the hoisting equipment have reached positions corresponding to the safe limit of travel or movement of any other part of the equipment, the engagement of this control member by the associated part of the equipment effecting a stopping of the hoisting equipment within safe limits of its travel.

A further object of the invention is to provide in hoisting equipment of the character described in the foregoing an automatic emergency safety control which may be adjusted through different positions, so that the hoisting equipment may be automatically stopped at any desired point. For example, the automatic stopping means of the hoisting equipment may be set so as to stop the same when some part being handled by the hoisting equipment reaches a desired position, this control being efiected independently of 2 whether the hoisting equipment has reached the extreme safe limit of its travel.

It is a further object of the invention to provide in hoisting equipment having air pressure controlled or actuated clutch and brake mechanism, a safety override control which will apply air pressure to discontinue supply of power to the drawworks drum and apply the brakes when any designated part, such as the traveling block of the hoisting equipment, reaches a predetermined position.

A further object of the invention is to provide a safety control for hoisting equipment having a control member disposed adjacent the drum of the hoisting equipment so that it will be engaged by the cable, when the cable has been spooledonto the drum to a predetermined point, and it is a further object of the invention to provide for this purpose an air valve device adjustable along the face Of the drum of the drawworks.

Further objects and. advantages of the invention may be brought out in the following part of the specification.

Referring to the drawings which are for illustrative purposes only,

Fig. 1 is a schematic view of the front face of a drawworks, with a part of my invention disposed in operative relation thereto.

Fig. 2 is a fragmentary sectional view taken as indicated by the line 2--2 of Fig. 1.

Fig. 3 is a fragmentary sectional View taken as indicated by the line 33 of Fig. 2.

Fig. 4 is a schematic View showing the manner in which air ducts of the emergency system are connected so as to control known parts of a drawworks.

In Fig. 1 I show the drum Ill of a drawworks, this drum l0 forming the part of a hoisting equipment on which the hoisting cable II is spooled. A characteristicof the winding of the cable I l on the drum in is that the cable is formed in consecutive layers a, b, and 0, etc. as shown in Figs. 2 and 3, these layers each consisting of turns of the cable lying close together as shown in Figs. 1 and 3.

As shown in Figs. 1 to 3, a guide or support I2 is provided, shown as a bar of round cross section carried by brackets l3 and M in a position parallel to but below the horizontal plane of the axis of the drum Ill. On the guide l2 there is a control device [5 having in the lower part of its casing an opening it through which the guide bar I2 extends. Screws [6- are providedfor clamping the device I in desired positions relative to the drum ID.

The control device I5 has a member I8 adapted to be engaged by the cable II when such cable I I has been wound on the spool II] to a desired position, such member I8 including a lever I9 pivotally supported at its lower end and having a small roller disposed in the path of the cable II, when such cable II is wound upon the drum ID to a desired extent. The control device I5 is adjusted upon the support I2 to such position that its roller 20 will be engaged by the cable I I when the traveling block 22 of the hoisting equipment is raised above the safe position indicated by the plane P faced downward from the crown block 23 of the hoisting equipment, as shown in Fig. 2. In Fig. 1 the rising portion 24 of the cable II is shown positioned to the left of the roller 20 of the movable member I8. It will be understood that as the rotation of the drum II] to wind in the cable II is continued, the portion 24 of the cable I I will travel rightwardly and will engage the roller 20. The roller 20 will be then moved rightward by the cable II and the emergency control of the device will be actuated to disconnect the drum I 0 from the source of power and apply the brakes associated with the drum I0, thereby stopping the hoisting equipment at or within the safe limit of the upward travel of the traveling block 22. It will be understood that if the rising portion 24 of the cable II is traveling from right to left on the drum III, the control device I5 may be reversed.

Drawworks such as employed in derricks are equipped with clutches and brakes of various designs, and actuating, controlling, and operating means are now provided for drawworks brakes and clutches, which means are operated or controlled by air pressure or air pressure differential acting against movable walls or diaphragms, etc. In the embodiment of the invention disclosed the control device I5 consists of a four-way valve, of which the valve art abounds. When the lever I9 of this valve device is in the position in which it is shown in full lines in Fig. 1 and Fig. 4, air under pressure from the supply line will be delivered through a flexible conduit 3I and piping 32 to the air inlet of a clutch control valve 33, which, as diagrammatically shown in Fig. 4, is connected by piping 34 with the master clutch 35 of the drawworks. Accordingly whenever the lever I9 is in the position in which it is shown in full lines there willbe available at the valve .33 a supply of air whereby the clutch 35 may be actuated into engaged position. It will be understood that when air pressure is released from the clutch 35, disengagement of the clutch parts will be effectuated.

From the valve device I5 a flexible conduit 3! and piping 38 extends to an expansible member 33 associated with the air brake valve 40 of the drawworks. The expansible device 39 is shown as a cylinder and piston mechanism having a valve operating part 42 which will be moved in response to the delivery'of air under pressure into the device 39 and will shift the lever 43 of the brake valve 40 from the position in which it is shown to brake operating position 43, whereupon air under pressure from the supply line 45 will be delivered through piping 46 to the air actuated brake 4'! associated with the drawworks drum so that its actuation will stop the rotation of the drum.

At any time prior to the shifting of the lever I9 rightwardly from the full line position in which it is shown in Figs. 1 and 4 by the rising portion 24 of the cable II, the clutch 35 and the brake 41 may be operated in their normal manner. If the inadvertence of the operator should permit the spooling of the cable I I to such extent that the lever I9 is shifted from its full line position toward and into the position in which it is shown by dotted lines 20a, air under pressure will be delivered to the expansible device 39 and the supply of air under pressure to the valve 33 and to the clutch 35 will be discontinued, with the result that the clutch will be released and the operation of the brake 41 will be assured. If the brake lever has not been already moved into its position 43, Fig. 4, the operation of air pressure in the expansible device 39 will be to move the lever 43 upward so that air under pressure will be fed from the supply line 45 through the valve 40 and the duct 46 to the brake 41, thereby stopping the hoisting equipment before damage can result from over-travel.

I claim as my invention:

1. In equipment of the character described having a source of power, mechanism including a drum with a cable spooled thereon, a fluid actuated clutch for connecting the source of power and the mechanism, a manually operated clutch control valve connected to said clutch, said valve having a fluid line leading to its inlet and fluid actuated brake means for stopping the mecha nism, said brake means having a control lever movable between on and off positions, the combination of: fluid operated means for moving said control lever to said off position; a fourway fluid control valve having a control member movable between first and second positions, the inlet of said valve being connected to a source of fluid under pressure, said four-way valve having means for feeding fluid under pressure to said fluid line of said clutch control valve when said control member is in said first position, and means operating when said control member is in said second position to release fluid pressure from said fluid line and apply fluid pressure to said fluid operated means; and an adjustable support for said valve control member enabling selective positioning of the valve control member in the winding path of the cable in a predetermined layer of the wound cable on said drum and for engagement and actuation thereby into said second position upon the winding of a predetermined amount of cable in said predetermined layer.

2. In equipment of the character described having a source of power, mechanism including a drum with a cable spooled thereon, a fluid actuated clutch for connecting the source of power and the mechanism, a manually operated clutch control valve connected to said clutch, said valve having a fluid line leading to its inlet and fluid actuated brake means for stopping the mechanism, said brake means having a control lever movable between on and off positions, the combination of: fluid operated means for moving said control lever to said off position; a four-way fluid control valve having a control member movable between first and second positions, the inlet of said valve being connected to a source of fluid under pressure, said four-way valve having means for feeding fluid under pressure to said fluid line of said clutch control valve when said control member is in said flrst position, and means operating when said control member is in said second position to release fluid pressure from said fluid line and apply fluid pressure to said fluid operated means; and a support for the valve control member positioning it in the winding path of the cable in a predetermined layer of the wound cable on said drum and for engagement and actuation thereby into said second position upon the winding of a predetermined amount of cable in said. predetermined layer.

3. In equipment of the character described having a source of power, mechanism including a drum with a cable spooled thereon, a fluid actuated clutch for connecting the source of power and the mechanism, a manually operated clutch control valve connected to said clutch, said valve having a fluid line leading to its inlet and fluid actuated brake means for stopping the mechanism, said brake means having a control lever movable between on and off positions, the combination of: fluid operated means for moving said control lever to said off position; a valve control member movable between first and second positions; valve means operated by said control member to apply fluid under pressure to said fluid line of said clutch control valve when said control member is in said flrst position, and operating when said control member is in said second position to release fluid pressure from said fluid line and apply fluid pressure to said fluid operated means; and an adjustable support for said valve control member enabling selective positioning of the valve control member in the winding path of the cable in a predetermined layer of the wound cable on said drum and for engagement and actuation thereby into said second position upon the winding of a predetermined amount of cable in said predetermined layer.

DANIEL MoLEAN DUNCAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

